In the past two weeks a problem surfaced on one of my servers which I haven't seen before. Periodically, the apache server just seems to hang and does not accept any connections.

When this happens, I can access the server through SSH with no problems, the load is always fine, there are no runaway processes either. Apache servers themselves seem to be online and running fine, but when I try to do 'lynx localhost', it gets stuck at 'request sent, waiting for reply'. It doesn't seem like it is tied to MySQL, I have a couple of sites which are pure HTML and it's the same story (no hung processes in mysqladmin either).

I'm not sure what is causing this, but restarting apache always fixes this - so it seems like it's an apache problem somewhere? (Recent one too). It's as if there is a blocking IO somewhere, and all threads decide to wait on it?

Has anyone come across a similar scenario? I'm really at a loss on how to go about debugging this one. I'm not sure how to reproduce it, and there isn't much I'm able to extract from it once it does happen.